Re: mpc880 linux-2.6.32 slow running processes
flat view
From: Scott Wood <hidden>
Date: 2011-01-05 23:58:23
On Wed, 5 Jan 2011 19:23:33 +0100 michael [off-list ref] wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/include/asm/pte-8xx.h b/arch/powerpc/include/asm/pte-8xx.h index dd5ea95..cb67076 100644 --- a/arch/powerpc/include/asm/pte-8xx.h +++ b/arch/powerpc/include/asm/pte-8xx.h@@ -32,7 +32,7 @@ #define _PAGE_FILE 0x0002 /* when !present: nonlinear file mapping */ #define _PAGE_NO_CACHE 0x0002 /* I: cache inhibit */ #define _PAGE_SHARED 0x0004 /* No ASID (context) compare */ -#define _PAGE_SPECIAL 0x0008 /* SW entry, forced to 0 by the TLB miss */ +#define _PAGE_SPECIAL 0x0000 /* SW entry, forced to 0 by the TLB miss */
What do you think is going wrong with the special bit on 8xx? Or might the change to set_pte_filter() alone be what fixed the problem?
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 5304093..1da03a8 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c@@ -173,21 +173,29 @@ static pte_t set_pte_filter(pte_t pte, unsigned long addr) pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS); if (pte_looks_normal(pte) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) || cpu_has_feature(CPU_FTR_NOEXECUTE))) { - struct page *pg = maybe_pte_to_page(pte); - if (!pg) + unsigned long pfn = pte_pfn(pte); + struct page *pg; + + if (unlikely(!pfn_valid(pfn))) return pte; - if (!test_bit(PG_arch_1, &pg->flags)) { + + pg = pfn_to_page(pfn); #ifdef CONFIG_8xx - /* On 8xx, cache control instructions (particularly - * "dcbst" from flush_dcache_icache) fault as write - * operation if there is an unpopulated TLB entry - * for the address in question. To workaround that, - * we invalidate the TLB here, thus avoiding dcbst - * misbehaviour. - */ - /* 8xx doesn't care about PID, size or ind args */ - _tlbil_va(addr, 0, 0, 0); + /* On 8xx, cache control instructions (particularly + * "dcbst" from flush_dcache_icache) fault as write + * operation if there is an unpopulated TLB entry + * for the address in question. To workaround that, + * we invalidate the TLB here, thus avoiding dcbst + * misbehaviour. + */ + /* 8xx doesn't care about PID, size or ind args */ + _tlbil_va(addr, 0, 0, 0); #endif /* CONFIG_8xx */ + + if (!pg) + return pte; + + if (!PageReserved(pg) && !test_bit(PG_arch_1, &pg->flags)) { flush_dcache_icache_page(pg); set_bit(PG_arch_1, &pg->flags); }
Rex, do you recall under what specific circumstances the _tlbil_va is needed? Is it possible that it will be caused by a dcbst in other contexts that are not dependent on the state of PG_arch_1? -Scott